001/**
002 * Copyright (c) 2012, The University of Southampton and the individual contributors.
003 * All rights reserved.
004 *
005 * Redistribution and use in source and binary forms, with or without modification,
006 * are permitted provided that the following conditions are met:
007 *
008 *   *  Redistributions of source code must retain the above copyright notice,
009 *      this list of conditions and the following disclaimer.
010 *
011 *   *  Redistributions in binary form must reproduce the above copyright notice,
012 *      this list of conditions and the following disclaimer in the documentation
013 *      and/or other materials provided with the distribution.
014 *
015 *   *  Neither the name of the University of Southampton nor the names of its
016 *      contributors may be used to endorse or promote products derived from this
017 *      software without specific prior written permission.
018 *
019 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
020 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
021 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
022 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
023 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
024 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
025 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
026 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
027 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
028 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
029 */
030package org.openimaj.hadoop.tools.twitter.utils;
031
032import java.io.DataInput;
033import java.io.DataOutput;
034import java.io.IOException;
035import java.io.PrintWriter;
036import java.util.Scanner;
037
038import org.openimaj.io.ReadWriteable;
039
040/**
041 * Convenience class which holds all the components required to calculate DF-IDF
042 * 
043 * @author Sina Samangooei (ss@ecs.soton.ac.uk)
044 * 
045 */
046public class WordDFIDF implements ReadWriteable, Comparable<WordDFIDF> {
047        /**
048         * Total number of tweets in all timeperiods
049         */
050        public long Ttf;
051        /**
052         * Number of tweets containing this word in all timeperiods
053         */
054        public long Twf;
055        /**
056         * Number of tweets in this timeperiod
057         */
058        public long tf;
059
060        /**
061         * Number of tweets containing this word in this time period
062         */
063        public long wf;
064        /**
065         * the measurment time period
066         */
067        public long timeperiod;
068
069        /**
070         * Helpful for reading
071         */
072        public WordDFIDF() {
073                Ttf = Twf = tf = wf = 0;
074        }
075
076        /**
077         * @param timeperiod
078         *            the timeperiod
079         * @param wf
080         *            Word count in this timeperiod
081         * @param tf
082         *            Tweet count in this timeperiod
083         * @param twf
084         *            Word count across all time
085         * @param ttf
086         *            Tweet count across all time
087         */
088        public WordDFIDF(long timeperiod, long wf, long tf, long twf, long ttf) {
089                this.timeperiod = timeperiod;
090                this.wf = wf;
091                this.tf = tf;
092                this.Twf = twf;
093                this.Ttf = ttf;
094        }
095
096        @Override
097        public void writeBinary(DataOutput out) throws IOException {
098                out.writeLong(timeperiod);
099                out.writeLong(wf);
100                out.writeLong(tf);
101                out.writeLong(Twf);
102                out.writeLong(Ttf);
103        }
104
105        @Override
106        public byte[] binaryHeader() {
107                return "".getBytes();
108        }
109
110        @Override
111        public void readBinary(DataInput in) throws IOException {
112                timeperiod = in.readLong();
113                wf = in.readLong();
114                tf = in.readLong();
115                Twf = in.readLong();
116                Ttf = in.readLong();
117        }
118
119        /**
120         * DF-IDF as defined by "Event Detection in Twitter by J. Weng et. al. 2011"
121         * 
122         * @return the DF-IDF score
123         */
124        public double dfidf() {
125                final double wf = this.wf;
126                final double tf = this.tf;
127                final double Twf = this.Twf;
128                final double Ttf = this.Ttf;
129                if (tf == 0 || Ttf == 0)
130                        return 0;
131
132                return (wf / tf) * Math.log(Ttf / Twf);
133        }
134
135        @Override
136        public int compareTo(WordDFIDF other) {
137                return new Long(timeperiod).compareTo(other.timeperiod);
138        }
139
140        @Override
141        public boolean equals(Object obj) {
142                if (!(obj instanceof WordDFIDF))
143                        return false;
144                final WordDFIDF that = (WordDFIDF) obj;
145                return that.compareTo(this) == 0;
146        }
147
148        @Override
149        public int hashCode() {
150                return (int) (timeperiod ^ (timeperiod >>> 32));
151        }
152
153        @Override
154        public String toString() {
155                final String format = "(wf=%s, tf=%s, Twf=%s, Ttf=%s, DFIDF=%.5f)";
156                return String.format(format, wf, tf, Twf, Ttf, dfidf());
157        }
158
159        @Override
160        public void readASCII(Scanner in) throws IOException {
161                this.timeperiod = in.nextLong();
162                this.wf = in.nextLong();
163                this.tf = in.nextLong();
164                this.Twf = in.nextLong();
165                this.Ttf = in.nextLong();
166        }
167
168        @Override
169        public String asciiHeader() {
170                return "";
171        }
172
173        @Override
174        public void writeASCII(PrintWriter out) throws IOException {
175                out.printf("%s %s %s %s %s", this.timeperiod, this.wf, this.tf, this.Twf, this.Ttf);
176        }
177}